There has been known a control device for a vehicular automatic transmission of the type including a plurality of hydraulically operated engaging elements and a hydraulic pressure control circuit arranged to control hydraulic pressures supplied to the plural hydraulically operated engaging elements. A shifting response is varied based on a preset relation depending on a predetermined condition. For instance, Patent Publication 1 (Japanese Patent Publication No. 9-79365) discloses a control device for a vehicular automatic transmission. With such a technology, in a manual shifting mode performed depending on the operation of a shift lever or the like operated by a driver, a backpressure of an accumulator is controlled associated with the engaging element related to the shifting in such a way as to obtain a relatively rapid shifting response.
On the other hand, during an automatic shifting mode performed depending on a vehicle speed and an accelerator depressed stroke or the like by referring to preset relationships, the backpressure of the accumulator is controlled associated with the engaging element related to the shifting in another way to obtain a further mild shifting response than that of the shifting response achieved in the manual shifting mode. Thus, the shifting response is varied depending on the shifting mode so as to obtain a rapid shifting response required for the manual shifting mode.
In addition to the above technology, other technologies have been known as those disclosed in Patent Publication 2 (Japanese Patent Publication No. 8-166058), Patent Publication 3 (Japanese Patent Publication No. 2000-213638) and Patent Publication 4 (Japanese Patent Publication No. 11-125330).
However, when performing the control which requires a response in hydraulic pressure related to the shifting, like a high-response shifting in a clutch-to-clutch shift in the conventional technology described above, following problem may be occurred. That is, the hydraulic pressure is applied with a delay in response which is caused by air mixed to working oil of the hydraulic pressure control circuit, resulting in occurrence of a turbine blow-up. To avoid such a defect, it has been required to develop a control device for a vehicular automatic transmission which can realize a shifting with a favorable response with suppressing a turbine blow-up during the shifting.